Gas turbine engines comprise a plurality of bladed rotors, each of which comprises a rotor and a plurality of rotor blades mounted on the periphery of the rotor. Each rotor blade has an aerofoil, a platform, a shank and a root. The rotor comprises a plurality of circumferentially spaced axially extending slots. The root of each rotor blade is arranged to locate in a respective one of the axially extending slots in the periphery of the rotor. The roots of the rotor blades are generally fir tree shaped or dovetail shaped and the axially extending slots are correspondingly shaped to receive the roots of the rotor blades.
The bladed rotor arrangement also comprises a plurality of lock plates arranged at a first axial end of the rotor and a plurality of lock plates arranged at a second axial end of the rotor to prevent the rotor blades moving axially relative to the rotor. The lock plates also act as seals to prevent fluid flowing through the axially extending slots in the rotor and axially between the shanks of the rotor blades and radially between the platforms of the rotor blades and the periphery of the rotor. The radially outer ends of lock plates at the first axial end of the rotor engage grooves defined by radially inwardly extending flanges on the platforms of the rotor blades and the radially outer ends of the lock plates at the second axial end of the rotor engage grooves defined by radially inwardly extending flanges on the platforms of the rotor blades. The radially inner ends of the lock plates at the first axial end of the rotor engage a circumferentially extending groove defined by the rotor and a seal plate arranged at the first axial end of the rotor and the radially inner ends of the lock plates at the second axial end of the rotor engage a circumferentially extending groove defined by the rotor and a seal plate arranged at the second axial end of the rotor. The seal plates are designed to remain rotationally stationary relative to the bladed rotor.
However, the arrangement described has suffered from a problem in that the seal plates may be able to rotate relative to the rotor when the gas turbine engine is operating, this may result in the seal plates becoming dislodged and in the case of a turbine rotor this may lead to leakage of coolant supplied to the turbine rotor and/or turbine blades and failure of the turbine blades.
Therefore the present disclosure seeks to provide a novel bladed rotor arrangement which reduces or overcomes the above mentioned problem.